The thunder clap of Google’s Matt Cutts’s Twitter post could be heard across the web this week with the announcement of the search engine’s latest update, Panda 4.0.

Of course the type of Panda I’m talking about isn’t a cute bear from China. It’s the name of an algorithm used by Google to filter out low quality content from search results.

The first Panda update in Feb, 2011 was fairly aggressive, affecting about 11% of queries on Google and millions of searchers. Panda also had an impact on more than a few website owners who fell from the search results like hail from the sky.

Barry Schwartz at Search Engine Roundtable reports that this most recent Panda update is expected to affect 7.5% of English search queries and with 12.5 billion searches per month on Google, that could be a pretty big storm for the SEO world.